Variation in virulence and its relation to hyphal growth and enzyme activity of Raffaelea quercivora , a Japanese oak wilt pathogen

The Japanese oak wilt pathogen Raffaelea quercivora and the platypodid beetle, Platypus quercivorus , cause serious mass mortality of Quercus spp. in Japan. Here, we present the first draft genome sequence of R. quercivora JCM 11526 to increase our understanding of the mechanism of pathogenicity and symbiosis with the ambrosia beetle.

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Raffaelea quercivora (Japanese oak wilt).

10.1079/isc.46687.20210198941 ◽

2021 ◽

Author(s):

Hayato Masuya

Keyword(s):

Tree Mortality ◽

Wood Products ◽

Oak Forests ◽

Native Range ◽

Oak Wilt ◽

Platypus Quercivorus ◽

Japanese Oak Wilt ◽

International Transport ◽

Geographic Regions ◽

Raffaelea Quercivora

Abstract Raffaelea quercivora, together with ambrosia beetle Platypus quercivorus as a vector, is the causal agent of Japanese oak wilt. P. quercivorus occurs from south to east Asia, including Japan, and is associated with trees in the Fagaceae family. R. quercivora is considered native to Japan, Taiwan, Indonesia, Thailand and Vietnam. In Japan, Quercus serrata and Q. crispula [Q. mongolica] are particularly susceptible to Japanese oak wilt, with high rates of mortality. Although there have been reports of the co-occurrence of R. quercivora and P. quercivorus outside of Japan, tree mortality caused by this species complex has never been recorded in these cases. R. quercivora is not on an alert list or listed as a regulated pest in any part of its native range. Although R. quercivora/P. quercivorus are not considered invasive, if they were introduced into susceptible oak forests, possibly via international transport of wood products, there is potential for them to cause extensive tree mortality in other geographic regions.

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Raffaelea quercivora (Japanese oak wilt).

10.1079/cpc.46687.20210104884 ◽

2021 ◽

Author(s):

Hayato Masuya

Keyword(s):

Tree Mortality ◽

Wood Products ◽

Oak Forests ◽

Native Range ◽

Oak Wilt ◽

Platypus Quercivorus ◽

Japanese Oak Wilt ◽

International Transport ◽

Geographic Regions ◽

Raffaelea Quercivora

Abstract Raffaelea quercivora, together with ambrosia beetle Platypus quercivorus as a vector, is the causal agent of Japanese oak wilt. P. quercivorus occurs from south to east Asia, including Japan, and is associated with trees in the Fagaceae family. R. quercivora is considered native to Japan, Taiwan, Indonesia, Thailand and Vietnam. In Japan, Quercus serrata and Q. crispula [Q. mongolica] are particularly susceptible to Japanese oak wilt, with high rates of mortality. Although there have been reports of the co-occurrence of R. quercivora and P. quercivorus outside of Japan, tree mortality caused by this species complex has never been recorded in these cases. R. quercivora is not on an alert list or listed as a regulated pest in any part of its native range. Although R. quercivora/P. quercivorus are not considered invasive, if they were introduced into susceptible oak forests, possibly via international transport of wood products, there is potential for them to cause extensive tree mortality in other geographic regions.

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A New Cytosporone Derivative from the Endophytic Fungus Cytospora sp

Natural Product Communications ◽

10.1177/1934578x1400900723 ◽

2014 ◽

Vol 9 (7) ◽

pp. 1934578X1400900 ◽

Cited By ~ 1

Author(s):

Tomoya Takano ◽

Takuya Koseki ◽

Hiromasa Koyama ◽

Yoshihito Shiono

Keyword(s):

Antimicrobial Activity ◽

Endophytic Fungus ◽

2D Nmr ◽

Ambrosia Beetle ◽

Oak Wilt ◽

Tree Disease ◽

Platypus Quercivorus ◽

Mass Spectral ◽

Screening Study ◽

Raffaelea Quercivora

Japanese oak wilt (JOW) is a tree disease caused by the fungus Raffaelea quercivora, which is vectored by the ambrosia beetle, Platypus quercivorus. In a screening study of the inhibitory active compounds from fungi, a new cytosporone analogue, compound 1, was isolated from the endophytic fungus Cytospora sp. TT-10 isolated from Japanese oak, together with the known compounds, integracin A (2), cytosporones N (3) and A (4). Their structures were determined by extensive 1D– and 2D–NMR spectroscopic and mass spectral analyses. Compound 1 was identified as 4,5-dihydroxy-3-heptylphthalide and named cytosporone E. Compounds 2 and 3 showed antimicrobial activity against Raffaelea quercivora.

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Spatial Distribution of Raffaelea quercivora in Xylem of Naturally Infested and Inoculated Oak Trees

Phytopathology ◽

10.1094/phyto-100-8-0747 ◽

2010 ◽

Vol 100 (8) ◽

pp. 747-755 ◽

Cited By ~ 21

Author(s):

Yukiko Takahashi ◽

Norihisa Matsushita ◽

Taizo Hogetsu

Keyword(s):

Small Area ◽

Fluorescent Substance ◽

Oak Wilt ◽

Conduction Loss ◽

Conductive Zone ◽

Inoculation Site ◽

Oak Trees ◽

Water Conduction ◽

Raffaelea Quercivora ◽

Distribution Water

Mass mortality of Japanese oak caused by Raffaelea quercivora due to Japanese oak wilt (JOW) has been tremendous since the late 1980s in Japan. We investigated detailed distribution of R. quercivora hyphae in a naturally infected Quercus serrata tree using fluorescein-conjugated wheat germ agglutinin and also examined spatial relationships between hyphal distribution, water conduction loss, and host reactions in xylem in inoculated Q. crispula saplings. Hyphae of R. quercivora elongated longitudinally in vessels and transversely in ray tissues in both naturally infected and inoculated Quercus trees. Hyphae were confined within a relatively small area near the inoculation site. Vessel dysfunction was also confined and overlapped with hyphal distribution. The reaction zone consisting of two types of fluorescent substance was formed surrounding the outside of the hyphal area in xylem and was always found in non-water-conductive zone. These results suggest that wilting of Quercus trees caused by JOW may not be induced by dysfunction of a small number of vessels, but by that of many vessels, and it requires that R. quercivora hyphae spread from many galleries bored by beetles during mass attacks.

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